Wednesday, April 27, 2011

The river Ghaggar which flows through the Indian states of Haryana, Punjab and Rajasthan and onwards into Pakistan had dried up in the latest Pleistocene. Therefore it may not have been the main water source for the later mid-Holocene Harappan settlements in that region and also likely was not the river Saraswati described in Rig-Ved.

That's the gist from three separate studies (pages 23, 24, 103) on the Ghaggar river basin presented at a meeting of the American Geophysical Union and summarized in Science.

The finding that the river Ghaggar likely dried up or had a drastically reduced flow in the latest Pleistocene is not that surprising from the perspective of the broader climatic regime existing from Late Pleistocene to Holocene. However, it is a surprising finding if you consider another theory of Ghaggar water flow - the glacially fed Ghaggar - which I will come to later.

First, the climate change perspective.

After the Last Glacial Maximum, monsoonal strength over the Indian subcontinent has fluctuated over a millennial scale resulting in dry and wet phases lasting a few thousand years each.

A late Pleistocene arid phase affecting north west India is well documented by various studies on sediments and landscapes in Rajasthan, Gujarat and western Maharashtra. See this paper by Mishra and Rajguru and references therein. The studies by Gupta et al and Maemoku et al which suggest that between 15,000 years and 10,000 years ago the Ghaggar basin shows signs of drying up, likely reflect this phase of aridity.

This late Pleistocene arid phase was followed by an early Holocene wet phase reflecting a stronger Indian monsoon. Then by mid Holocene another episode of aridity set in which coincided with the ultimate demise of the Harappan civilization.

I don't want to comment here on the implications of these studies regarding water dependency of the Harappan civilization or the Vedic Saraswati problem.

Instead I want to point out that these new geological findings by Gupta et al and Maemoku et al do hint at an answer to another interesting geological question.. whether the Ghaggar was a glacially fed river in the past.

It has been hypothesized that the Sutlej and the Yamuna, both glacially fed rivers, flowed into the Ghaggar during the Holocene and by late Holocene around 2500 B.C to 1800 B.C avulsed or shifted course to their present positions. So along with climate change, rivers changing courses is another explanation given for the reduced water flow of the Ghaggar by late Holocene.

I think the time frame over which this problem has been thought out has a bearing on the choice between the climate change and river avulsion theories. If you only consider the Holocene and one episode of a river drying up (a larger Ghaggar drying up by 1800 B.C) then a Late Holocene river avulsion event seems as plausible an explanation as a climate change one.

But if more studies confirm Gupta's and Moemuko's finding that the Ghaggar had indeed dried up in the late Pleistocene then that would weaken the theory that the Yamuna and Sutlej flowed into the Ghaggar until the late Holocene.

A glacially fed Ghaggar would likely not have dried up even during the late Pleistocene arid phase. Summer melting of the large Himalayan glaciers built up through the Last Glacial Maximum would have maintained enough water flow in the Ghaggar throughout the year.

The simplest explanation of these alternating phases of river drying and rejuvenation through the late Pleistocene into the Holocene is that the Sutlej and the Yamuna never flowed into the Ghaggar. The Ghaggar was not glacially fed, but by streams originating in the lower and sub Himalayas, and its fortunes always depended on the strength of the Indian monsoons.

One scenario of rivers shifting courses that does fit this extended late Pleistocene-Holocene time frame depends on the Sutlej and / or the Yamuna getting diverted away from the Ghaggar much earlier, around 14,000 years ago or so. The drying of the Ghaggar brought out by these two studies then reflect a combination of river avulsion and climate change.

Either way, these new findings make it cumbersome to support the theory of a glacially fed Ghaggar river.

[Update 2012):New geochemical and geomorphological studies strongly suggest that Yamuna and Sutlej stopped flowing in to the Ghaggar /Saraswati thousands of years before the Harappan civilization. See these posts for more on this topic -

Thursday, April 21, 2011

Filmmaker Werner Herzog got a once in a lifetime opportunity to enter the Chauvet caves in France which has some exquisitely preserved rock paintings, dated to about 30 thousand years ago. He made a 3D movie of the interior of the cave.

GROSS: And they wanted you to keep on the walk so that you didn't contaminate the rest of the cave, yeah.

Mr.
HERZOG: Oh, you never - can never touch anything. It's not just
contaminating. There are footprints, fairly fresh footprints. You do not
want to superimpose your print of your hiking boot upon it. There's...

GROSS: Oh, over the cave-bear print. Yeah.

(Soundbite of laughter)

Mr.
HERZOG: Yes, you just don't do this. And there's a footprint of a
child, maybe eight-year-old, this very mysterious. We couldn't film it.
We were not allowed, because it was deep in the recess of the cave.

The
mysterious thing is that next to this footprint, probably a boy,
probably around eight years old, parallel to it runs the footprint of a
wolf. And I was very, very puzzled: Did the wolf stalk the boy? Or did
they walk together as friends? Or did the wolf leave its footprints
5,000 years later? It's stunning. The lapse of time is completely and
utterly stunning.

What a context for an artist to let loose his imagination! The Cave of Forgotten Dreams indeed.. but also the Cave of Infinite Imagination.

Werner Herzog also recently joined physicist Lawrence Krauss and author Cormac McCarthy in a conversation about how science and art inspire each other. Speaking about the differences between art and science Krauss remarks:

Tuesday, April 19, 2011

Biologist Ursula Goodenough is cautiously upbeat about high school biology portions in the U.S. She has been reviewing them and finds that evolution finds a mention in most of the standards. Human evolution however is included in the standards of just one state - Florida.

Now while this may be seen as an improvement, a survey of how well evolution is actually taught in high school doesn't sound too upbeat.

Some time back a number of science news outlets wrote about the results of a survey by two political scientists Michael Berkman and Eric Plutzer on the state of high school evolution education in the U.S.

Their survey showed what was always known, that the majority of teachers don't take teaching evolution seriously. This may be because they are not trained enough to tackle the subject matter or are intimidated by creationist students and parents or are creationists themselves and refuse to teach evolution.

In India, high school biology classes lack the drama unfolding today in the U.S. Evolution is simply a non-issue here. The biology syllabus is set by a central national level school board. Unlike the U.S. there is no scope for local school boards populated by religious fundamentalists to influence science standards. There is no demand for textbooks to be plastered with stickers urging students to consider "alternative" theories and there are no threats issued to biology teachers.

I've flipped through the chapters on evolution of the CBSE board for 10th and 12th. They cover a lot of the basics and include a unit on human evolution too. One might quibble about a few things here and there, but a dedicated teacher with an interest in evolution will find a lot to build upon and make the subject interesting for students. I can't comment on the quality of teaching of evolution. Likely it varies depending on the skill and training of individual teachers.

What is lacking though is controversy!

Although biology syllabus is set at a national level, there is always scope for parents to register complaints to local schools about what is being taught in class. Most parents in India too are deeply religious. We too have our share of religious fundamentalists. But fights over teaching of evolution are unheard of in urban India.

I think one reason is the diminished role science plays during the high school phase. In India, applied and technical careers are preferred over a career as a scientist. Hardly anyone talks about becoming an evolutionary biologist. Hardly anyone looks at the science syllabus as an inspiration for becoming a scientist. So, that the theory of evolution is important or alternatively is a controversial subject rarely becomes a topic of discussion between parents, teachers and children.

The other reason I think is our obsession with preparation for examinations. Despite more choice in careers and separate entrance exams for various technical degrees, standards 10th and 12th are still seen as exams that will set the future course of your life, an important stepping stone to lucrative career paths. Most parents don't want to get into fights with school authorities in the fear that any disagreements might adversely affect their child's performance in school.

They look at the syllabus not for its educational merit or in case of evolution in fear over what it might be doing to the moral values of their children, but how easily it can be mastered to score the highest possible marks. Even for religious fundamentalists, the practical matter of their child's performance in exams trumps any personal conflicts with evolution they might be harboring.

More generally, evolution is a non issue here because no one thinks of evolution as any different from other topics. It is simply just another module to be mugged up for the all important exam.

Sunday, April 17, 2011

It's always big news when an Indian academic starts a blog. Here is a very interesting one. Sheila Mishra is writing with gusto on her work and on the work of colleagues in the field of archaeology and anthropology.

Dr. Mishra is with the Department of Archaeology, Deccan College, Pune. She also maintains a publication page where you can download many of the papers on various aspects of the Indian Quaternary.

The content on the blog so far is mostly on the Indian archaeological record of various lithic cultures ("stone age cultures") with implications for human migration and evolution.

Dr. LEAKEY: ..... In fact, there are very few African leaders who believe in human evolution and science.

FLATOW: Is that right?

Dr. LEAKEY: And it's very, very worrying, because Africa's problems will only be resolved by African scientists working on those problems. And if we don't teach science from early on, we're not going to get out of this hole, because nobody is going to pull us out of the hole, because they're in one themselves.

FLATOW: Does it make it hard to excavate in these African countries if they don't believe?

Dr. LEAKEY: Funny enough, it doesn't. Because if they don't believe we're looking for human ancestors, they don't care what you're doing.

FLATOW: What an interesting answer.

(Soundbite of Laughter)

FLATOW: You could be digging on the moon for...

Dr. LEAKEY: Exactly. For something else.

FLATOW: ...for - because of - we don't - whatever you find is not going to prove what you think it's going to prove.

Dr. LEAKEY: That's exactly the attitude. And so, thus far, it's been beneficial, if you like.

You can dig for bones as much as you want in the remote rift, just don't introduce your findings into the science syllabus.

Mr. FISHMAN: And all the water on Earth was actually formed in space,
in interstellar gas clouds. And it was delivered here when the Earth
was formed, or shortly thereafter, in exactly the form it's in.

So
all the water on Earth - the water in your Evian bottle, the water in
your glass of water, the water you use to boil a pot of spaghetti - all
that water is 4.3 or 4.4 billion years old. No water's being created on
Earth. No water's being destroyed on Earth. And what that means is the
whole debate about reusing wastewater is kind of silly, because all the
water we've got right now has been used over and over again. Every drink
of water you take, every pot of coffee you make is dinosaur pee,
because it's all been through the kidneys of a Tyrannosaurus Rex or an
Apatosaurus many, many times, because all the water we have is all the
water we have ever had.

And to me, that's
actually good news. Water is incredibly resilient. It's unlike fuel or
other natural resources. It can be used over and over and over again,
and it emerges - except for needing to be cleaned, ready to use again -
exactly as water.

That's thinking of recycling well beyond the usual discussions of wash-basin to your lawn. He talks about that too and a lot more in a quite informative talk.

Did you know why the launch pad of the space shuttle is covered in a cascade of water during launch?

And you would naturally think that that has something to do with the
heat and the flame. In fact, the water on the launch pad of a space
shuttle launch is a sound-dampening mechanism for the space shuttle. The
space shuttle is so loud that the sound would ricochet off the concrete
and metal launch pad and tear the space shuttle apart, literally
destroy it, before it cleared the pad without the water.

Monday, April 11, 2011

How about an elegant light grey suit? ..Will help you keep away the scorching Indian sun.

That's an unnamed senior Indian government official at a photo-op (source) leaning over a row of dinosaur eggs found recently from the Upper Cretaceous (about 80 million years ago according to the report) of the Narmada river valley central India.

The Narmada river flows westwards within an ancient rift zone which originated during early Proterozoic and has been reactivated to become a sedimentary basin several times thereafter. Mid-late Cretaceous was one such time of reactivation, several linear east west oriented basins forming in response to the crustal stresses generated as India wrenched itself away from Africa, then Madagascar and then Seychelles.

Mid late Cretaceous was a time of globally high sea levels. Marine incursions into these basins took place from the west, but there are fluvial (river) and lacustrine (lake) sediments also in the Cretaceous basins of central India. The recently found dinosaur eggs along with other reptilian fossils are from lacustrine and fluvial deposits preserved in the Dhar district of Madhya Pradesh.

The terrestrial Cretaceous sediments of central India have been yielding a rich trove of dinosaur and reptilian fossils. These are thin patchy deposits. Large portions of these deposits are likely buried under the Deccan basalts, entombed by lavas that began erupting around 65 mya. The deposits that do outcrop are being threatened by increased farming activities and urbanization. So, its really good to hear that the Madhya Pradesh government is planning on creating a dinosaur park which will hopefully protect at least some of these fossil sites.

Meanwhile.. I found this geological map of Madhya Pradesh from the Geological Survey of India Geology and Mineral Map series which is worth sharing.. below is a portion of the map showing western Madhya Pradesh. The red arrow indicates the general location of the Upper Cretaceous outcrops (blue) of Dhar district.

Thursday, April 7, 2011

Marc Kaufman, science writer and national editor at Washington Post talks with Dave Davies of NPR's Fresh Air and quite expertly summarizes the current state of knowledge on the possibility of extraterrestrial life.

From the NPR page -

Scientific interest in extraterrestrial life has grown in the past 20
years. The field of astrobiology now includes researchers from a wide
variety of disciplines — microbiologists studying bacteria that survive
in the most extreme conditions on Earth; astronomers who believe there
may be billions of planets with conditions hospitable to life; chemists
investigating how amino acids and living organisms first appeared on
Earth; and scientists studying rocks from Mars are seeing convincing
evidence that microbial life existed on the Red Planet.

I'm not sure I agree with the last sentence. There is convincing evidence of past water on Mars and perhaps water or ice beneath the surface today, and of sedimentary deposits and of methane being let off in Martian soil due to some type of chemical reaction.

There are strong opinions on what all these could mean but no convincing evidence either in the form of physical fossils or biochemical markers of microbes past or present.

Still we have come a long way from the times when SETI and the Drake equation and Jodie Foster listening for the telltale transmission from intelligent beings fired our imagination about life somewhere far away in the cosmos.

Nowadays scientists working on extraterrestrial life get excited about things closer to home like extremophiles a kilometer down in an acid mine, wormy micro structures in a Martian meteorite and methane emissions from Martian soils.

That counts as progress in one of the most important fields of human enquiry.

Monday, April 4, 2011

At a press conference in Delhi last Friday, the Honorable Minister of Forest and Environment Mr. Rairam Jamesh announced that the country will see a strategic shift in its approach to geological and ecological mapping. Our scientists he said have mapped the geology and ecology on a regional scale. Now, we want more detailed finer resolution maps. For that we have come up with a novel method.

Take for example earthquakes. The recent events in Japan has helped us see the bigger picture in terms of the relationship between nuclear power plants and earthquake risk he said. We've done a survey of all our current and some future nuclear plants and realized that at all these sites detailed mapping revealed previously unknown faults. As a result, all these sites now fall in a higher earthquake risk zone than previously thought. Its incredible.. you site a nuclear plant and you will find a new fault.

he continued... The correlation is very strong and we intend to put it to use for making detailed geological maps of the country. We propose tens of new nuclear plants in areas where the geology is not that well known. Once the sites are approved and construction begins we are confident that we will find new faults, enabling us to upgrade our seismic risk zonation map the Minister said.

Asked how the process will work the Minister explained-

Our experience tell us that once construction starts, civic society gets nervous and begins to take a keen interest in the occurring and future collateral damage that is inevitable at these sites. The first Environmental Impact Assessment (EIA) report is critically evaluated and shown to be not adequate.

This will force us to order another more rigorous examination of the site. It is at this stage that the new study will reveal what was missed in the first report. New geological features will be discovered and a more thorough understanding of the earthquakes risks will be achieved.

So, the first EIA is absolutely crucial to this strategy he stressed.

The report's sloppy science is what galvanizes the second detailed study. And the first EIA also serves a secondary purpose of generating employment. Traditionally, for this first report, we hire consultants who otherwise won't find employment anywhere else.

This is the spin of the project the Minister said.

You mean this is the spin-off generated by the project, asked a reporter.

Yes exactly, the Minister agreed.

The Minister then expanded on the plan. We won't restrict this new strategy to just nuclear plants. There are plans to start construction of new coal powered thermal plants in scenic, picturesque and forested areas in the hope that we make new discoveries about the ecology and bio-diversity of the region following the same two step process outlined earlier.

Build and you will find summarizes this paradigm shift nicely the Minister said.

A reporter was quick to see a parallel with urban development and asked about it.

Yes, that's a smart analogy the Minister said. Build it and they will come has long been a strategy for urban rejuvenation. For example, for long we have wanted to economically rejuvenate areas occupied by slums. We want people who have benefited from the recent economic growth, the noveau riche, to enjoy and spend their money. The best way to do that was to demolish the slums and build malls. People are now thronging to these temples of modern India and helping spur economic growth.

The Minister fielded one last question. Will the discovery of increased earthquake risk or ecological sensitivity stop all this construction?

The Minister frankly answered - Well, our job is one of scientific discovery, a fault here, a new species of frog there, perhaps an owl or a woodpecker or two. We want to develop a synergy between different scientific organizations and give a boost to basic research.

The decision about the fate of the new plants will be taken by the synergistic association of two other entities - the polity and the industry.

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ABOUT THIS BLOG

I am a Sedimentary Geologist. On Rapid Uplift I write mostly about topics within the geosciences, but sometimes on biological evolution and environmental issues. I like to travel and in my free time I teach 12 year old kids soccer and rugby.